I've got a Kindle Fire and the device is great. It does everything I ask of it -- plays my movies and shows (from Amazon and from Netflix), games, and web surfing. And with GMote, it controls my Mac almost as well as Rowmote does on my iPhone 4.
I only have three issues with it, really.
1 - The pixel density is too low for reading my Star Trek comics comfortably.
2 - Even at minimum brightness, the screen is too bright for reading before bed.
3 - It has trouble with all but the most basic PDF files.
Completely off topic: I've often lamented that they aren't making tablets with cellular connectivity. I don't need a pocket-size device, or even want one. An iPad with a bluetooth headset (and maybe an open-faced carrying case with handle) would be just perfect. A dashboard interface/charger mount in the car would be cool too - let the thing control my radio, be my GPS, call my wife, entertain the kids, and more. The ultimate all-in-one.